10: Recursion

Input two positive integer numbers. Write a program to multiply them. You are only allowed to use + and – operations, i.e. multiplication and division operations are not allowed.

Given a string S. Write a program to reverse it.

A word is considered elfish if it contains the letters e, l and f in any order. For example, the following words are elfish:
whiteleaf, tasteful, unfriendly, waffles
Input a word. Output YES if the word is elfish and NO otherwise.

Input positive integer n. Write a program to check whether n ir prime or not. If n is prime, output YES, otherwise output NO.

Input a non-negative integer n. Write a program to reverse the number. For example, if n = 2560, the output should be 652.

Input n, the size of an array.
Input n elements – integer numbers – and store them in an array. Output the smallest value in the array.

The legend of the temple of Brahma tells:

• There are 64 golden disks on one page sorted from the largest in the bottom to the smallest on the top.
• There are three pegs in total (two others are initially empty).
• The universe will end when the priest will move all the disks from the first peg to the last following the rules:
  • move one disk at a time
  • a move consists from taking one disk of a peg and putting it on another peg (on an empty peg or on top of other disks).
  • cannot put a larger disk on a top of a smaller disk.

With 64 disks at 1 sec. per disk this would take roughly 585 billion years.
It is required to move all disks from peg A to peg B using peg C as the intermediate one. Write a program to input the number of disks n and to output all required moves.
For example, if n = 2, your output should be:
A -> C
A -> B
C -> B

Given a string which contains arithmetical expression consisting of positive numbers from 1 to 9 and arithmetical operations (+, -, *, /). The expression always starts from a positive number. Output the value of the arithmetical expression.
For example, if the given expression is:
2+5*6*3-2*5*6/3-2, The answer should be: 70